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Phosphor Bronze

What Is Phosphor Bronze

Phosphor bronze is an alloy of mainly copper, tin and phosphorus that is widely known for its strength, durability, fine grain and low coefficient of friction. It is usually manufactured it in the form of wires, tubes, bars, plates and sheets. It comes in a wide range of grades and has a moderate price [7].

Phosphor Bronze

Composition [2]

Copper 93.4-95.32%
Tin 4.2-5.8%
Zinc 0.30% (max)
Iron 0.10% (max)
Lead 0.05% (max)
Phosphorus 0.030-0.35%

Properties and Characteristics of Phosphor Bronze

The alloy has great fluidity and castability in the molten state owing to the presence of phosphorus. Tin increases its corrosion resistance and strength [8].

Phosphor Bronze Washers

Physical Properties

Color/appearance Reddish (in most cases) [7]
State at room temperature Solid [7]
Melting point/freezing point 880-1025°C [3]
Density 8800 kg m3 [3]
Machinability 20% [3]
Thermal Conductivity 50 W/(m K) [3]
Electrical Conductivity (relative to copper) 15% [9]
Heat capacity 0.38 J/g °C [3]
Resistivity 13 micro-ohm-cm [4]
Hardness (Rockwell B) 85 [3]
Tensile strength (ultimate) 550 MPa [3]
Yield strength 450 MPa [3]
Young’s modulus 110 GPa [3]
Modulus of elasticity 110 GPa [3]
Friction coefficient (with steel) 0.35 [6]
Coefficient for thermal expansion 17.8X10-6/0C [5]

Uses

  1. Typically for making springs, sleeve bushings, bearings, welding rods, nuts, bolts, etc [7, 8].
  2. To make the suspension coil of moving coil galvanometers because it doesn’t oxidize easily, is non-magnetic and has low torsional constant [8].
  3. Making jewelry, knife and lock washers, guitar strings, harmonica reeds, dental bridges [7]

Phosphor Bronze Strings

Is It Dangerous

The fumes or dust of the alloy is toxic to humans. Hence, contact with skin, clothing and eyes should be avoided. In solid form, the material is not hazardous [1].

Phosphor Bronze Bushes

Interesting Facts

  • When exposed to air, a beautiful patina forms on its surface that makes it suitable for artistic applications [10].

Phosphor Bronze Bar

References:

  1. Phosphor Bronze Alloy Material Safety Data Sheet – Fiskalloy.com
  2. Phosphor Bronze Physical & Chemical Properties – Meadmetals.com
  3. Phosphor Bronze 510 – Elginfasteners.com
  4. Ness Engineering Technical Data Metal/Alloy Resistivity – Nessengr.com
  5. Co-efficient of Thermal Expansion Data – Repairengineering.com
  6. Friction and Friction Coefficients – Engineeringtoolbox.com
  7. Phosphor Bronze Powder – Americanelements.com
  8. Alloy: C51000 Phosphor Bronze 5% A Spec Sheet – Concast.com
  9. Electrical Conductivity of Materials – Bluesea.com
  10. Henley’s Twentieth Century Formulas Recipes Processes Vol1 – Chestofbooks.com

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